SD-CAB Scientific Research Programs

Algal physiology and photosynthesis

Ultimately, the goal of creating energy from biomass is related to the fundamental process of photosynthesis whereby cyanobacteria, algae, and vascular plants absorb sunlight energy, fix CO2, produce O2, and assimilate inorganic nutrients and trace elements into organic molecules (e.g. sugars, lipids, proteins, nucleic acids, etc.). The cellular physiological performance criteria (growth rate, yields of biochemicals), are macroscopic indices of sub-cellular processes that are regulated by the environment and affect expression of functional proteins that in turn regulate metabolism and sub-cellular properties. Different strains have different genetic information that regulates — in part— the type and accumulation of lipids
(or other biomolecules). Expression of the genome however, is plastic, meaning that within certain constraints, more (or less) biosynthesis and/or accumulation of any compound (e.g. lipids) may occur. Environment (light, temperature, nutrients) regulates the biosynthetic transformations, availability of nutrients required for growth, and the flux of light energy into the cell. All these affect the expression of the genome, and ultimately the relative fractions of cellular components, including lipids or other bioenergy molecules. Details of these processes and how they affect yields of bioenergy molecules are poorly known and are an essential and complementary requirement to genomics and proteomics research.

Genomic analysis of diverse algal species.

A key limitation to progress in developing sustainable energy from algae is the lack of genetic and genomic information on a variety of important algae. To date, only a few algal genomes have been sequenced and annotated. The natural diversity of algae and their chloroplasts is tremendous, with organisms capable of living in extremes of pH, osmolarity, and temperature. Algae also vary in their growth rates and fuel precursor composition. Knowledge of the genetic basis of these properties will allow scientists to exploit the full potential of these natural qualities for biofuel production. In addition, this genomic knowledge will further open the door to developing new strains of algae that can generate valuable fuel molecules not produced in naturally-occurring algal species.

Molecular genetic analysis of algal gene expression.

In addition to obtaining DNA sequence information on algal genomes, we need to understand how algal genes are regulated and how the expression of these genes results in the production of biofuel molecules. These basic studies on gene expression in algae, which will complement the genomic and proteomic analysis described below, are essential to understanding the biology of algae and how they produce the biofuel molecules that we need.

Proteomic and metabolomic analysis of algal species.

Since a single gene can code for different enzymes with widely diverse functions, we need to complement the genomic information we generate with various methods of protein analysis including chemical biology, mass spectrometry, and informatics technologies to understand how they work. (These large-scale approaches to protein science have been collectively termed proteomics.) A fuller knowledge of algal metabolites—natural byproducts of algae growth—and how these can be altered will be crucial to future engineering efforts.

Development of molecular tools and protocols for engineering biofuel production in algae.

A key aspect of the Center research programs is to develop the molecular tool kit that can be used to generate superior strains of algae capable of producing biofuels economically and at a scale that can have real impact on the fuel needs of this country. The protocols and molecular techniques for metabolic engineering algae are truly in their infancy and developing these tools will not only aid biofuel production but will significantly advance our understanding of algal physiology and metabolism.

Development of Co-products in algae.

A benefit of accelerated research on algae will be its applications in other areas besides energy production, including industrial enzymes and medical therapeutics. SD-CAB labs have produced therapeutic proteins in algae, including anti-cancer therapeutics that may allow for greatly improved cancer therapy. We are also investigating the sustainable production of chemical feedstocks that are currently derived from petroleum refining.

Aquatic Microbial Ecology

Commercial algal cultures in open systems will have risks associated with viruses, bacteria and grazers. Even for closed photobioreactors it is very difficult to prevent development of bacterial communities or to prevent risks associated with viruses. For algae mass culture, maintaining a pure culture of a single algal strain can only be achieved with relatively expensive closed photobioreactors and ultra-clean systems for delivery of media, inoculum and harvesting. Such systems are industrialized for diverse high value products, but may not prove economical for producing large mass of fuel at market prices. It is therefore essential to understand the microbial community ecology in mass culture systems to minimize the risk of scale up. SIO scientists are world leaders in microbial ecology; this expertise will be applied to diagnose and understand problems associated with microbial ecology. Our understanding of microbial ecology risk modes will inform the design process for scaled systems for biofuel production that minimizes these risks.